Fundraisers from Payroll Giving in Action have started using the pen to record donors' account information. It recognises the words being written on the paper and sends them via Bluetooth to a central database.
Previously, such information had to be entered manually into a database, which took two weeks. The system, from technology firm Destiny, will allow an employee's first donation to be taken a month sooner.
"Once people have made the decision, they want to begin donating straight away, and this helps them to do it," said Jeremy Colwill, director of PGA.
He said the design was deliberately simple to avoid giving the impression of expensive hardware.